The present invention pertains to a friction element assembly, such as a clutch or brake, for a transmission of a motor vehicle and, more particularly, to a friction element assembly configured to prevent a snap ring, securing the friction element assembly, from exiting a groove provided for the snap ring.
In a typical transmission for a motor vehicle, there are a number of friction element assemblies, such as clutches or brakes, each friction element assembly including multiple plates and friction members. During operation of the vehicle, in order to apply a friction element, a piston assembly contacts and then compresses the plates and friction members together. For this compression to occur, movement of the plates and friction members must be restricted in some way. Generally, a snap ring is provided for this purpose, although other portions of the transmission are sometimes used when allowed by the structure of the transmission.
During assembly of the transmission, the plates and friction members of the friction element assembly are installed followed by the snap ring. To install the snap ring, it is contracted, placed near a groove in a housing of the friction element assembly and then allowed to expand back to its default size such that the snap ring enters the groove. This tendency to expand acts to hold the snap ring in place. However, the snap ring may be deformed by the forces applied to it and thereby exit the groove, especially if the groove is relatively shallow such that a smaller percentage of the snap ring is located within the groove. If the snap ring exits the groove, the friction element assembly cannot be actuated by its piston assembly. In certain friction element assembly configurations, though, it is beneficial to use a shallower groove as this reduces stresses in the housing. Therefore, there is a need in the art for a friction element assembly design that prevents a snap ring thereof from exiting a relatively shallow mounting groove once the snap ring has been installed.